In the construction industry there is a composite material generally used, a paste-type material comprising other materials to gain volume and that has excellent mechanical properties, this material is concrete. Through history, concrete has been undergoing important modifications ranging from masonry binding to be a principal element in constructions of slim or thin-walled and resistant or strain and stress resistant structures, such as reinforced concrete.
Concrete has different classifications primarily based on its ability to resist strains and stress or strength under compression and the time required to acquire such strength (set or dry). In this manner, normal resistance concrete and high-resistance or fast-resistance concrete can be obtained. It is important to mention that there is a national and international industry that has generated diverse material to be combined with concrete in order it to acquire new properties. These materials are known as additives, fluidizers, die retardants, waterproofing agents, air fillers and strain-reinforcing fibers. In other words, concrete is a mixture that can accept a number of external agents (additives) without detriment of its main feature (compressive strength) and with a gain in its original properties.
On the other hand, the interest in developing composite materials has been increased in recent years, combining two or more components and which properties allow their use in diverse areas. More recently, the interest in using nanometer-scale materials for manufacturing nanocompounds with improved properties has been increased. Carbon nanotubes are excellent candidates for manufacturing nanocompounds as these can be 100 times more strength than steel but six times lighter than this.
An example of the above is the document WO2009/099640 that discloses a method for manufacturing composite materials comprising cement reinforced with dispersed carbon nanotubes, by applying ultrasonic energy and using a surfactant to form a fluid dispersion of carbon nanotubes and mixing the dispersion with cement such that carbon nanotubes can be well dispersed in the cementitious matrix.
Also, document US2008/0134942 discloses the use of carbon nanotubes in cement composites, wherein cement, aggregated material, carbon nanotubes and plasticizer are used.
Within the different carbon nanotube types, there are single-wall structures and multiple-wall structures, besides a differentiation according to elements to be bound to nanotube walls by means of physical and/or chemical treatments. For example, carbon atoms can be replaced by different elements in the walls. Among these are nitrogen, phosphorus, potassium, silicon, oxygen, boron, etc. Additionally, there is a possibility to have covalent groups covalently bound to nanotube walls, particularly methyl, carbonyl, hydroxyl groups, etc. The modification of tube surface either by doping or functionalizing increases surface reactivity thereof, which is essential to create strong interactions among nanotubes and matrixes in question such as cement or concrete.